Went yard saling and have some questions.

Well, the general trend at this site is to call UGF an old school filter. If you ever got honest answers that were verifiable, most of them never maintained tanks on UGF nor maintained them correctly. They just repeat what the have heard never really referencing any real experience with them.

They are, $ for $, the most inexpensive way to generate a large surface area for bacteria. The powerhead driven style are much more effective than a simple airdriven one. The issues come into play when you fail to properly maintain your tank with water changes and gravel vacs. The substrate can trap waste and uneaten food, that needs to be cleaned out.

I have been using them, with and without plants for 30 yrs. Never have I seen a properly maintained one get clogged as at least a dozen folks that I know of will tell you. They lack somewhat in a true mechanical filtration for anything in the water column until it can settle and fine stuff will still continue to float around.

The RUFG, reverse undergravel filter, is the better method to run them, where you are pushing water down the lift tube, under the plates, and back up thru the substrate. This still uses the substrate as your bacteria surface area and pushes the debri into the water column, to be removed by other mechanical filter methods. It also reduces gravel vacs required. There are very few dead spots in an RUGF set up.

rb loves them and they work. i am not a fan i dont like anything that takes up tank space but again thats just me.

second nature 840 - GPH 221

To create circulation in the tank to prevent dead spots and to help agitate the surface for more effective gas transfer.